Photographic focus adjustment apparatus

ABSTRACT

Photographic focus adjustment apparatus for varying the axial position of a camera objective lens or lens element is disclosed in each embodiment as comprising lens carriage means having external threads, lens carriage support means having internal threads mating with the threads on the lens carriage means, sliding key means for preventing rotation of the carriage means with the carriage support means while providing freedom of axial movement of the carriage means, and manually operable actuating means for effecting selective rotation of the carriage support means to cause the carriage means and thus the lens (or lens element) to move along its axis. In one embodiment depicted the carriage support means, as well as the carriage means, moves axially upon rotation thereof in such a way as to obviate exposure of any threads to atmospheric dust and other foreign matter. In another embodiment disclosed, contamination of the threads is avoided by the provision of an expansible bellows between the lens carriage means and the camera housing.

United States Patent 1191 Farrell et al.

Jan. 9, 1973 [54] PHOTOGRAPHIC FOCUS ADJUSTMENT APPARATUS [75]Inventors: George J. Farrell, Bedford; Walter R. Lyon, West Roxbury,both of Mass.; Loring K. Mills, Hampton, N.H.; Reginald 0. Shaw,Westhampton, Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Nov. 27, 1970 [21] Appl.No.: 93,340

[52] US. Cl. ..95/45, 95/34, 95/44 R [5 l] Int. Cl. ..G03b 3/02 [58]Field of Search ..95/39, 45, 44; 285/226 [56] References Cited UNITEDSTATES PATENTS 3,036,148 5/1962 Swerdlow ..285/226X 2,357,327 9/1944Harris et al ..95/45 2,270,311 l/l942 Kende et al. ..95/45 3,447,4396/1969 Rice ..95/39 2,238,498 4/194] Mihalyi.. ..95/45 2,972,291 2/1961Kindig ..95/45 3,251,285 5/1966 Uterhart ..95/45 Primary Examiner-SamuelS. Matthews Assistant Examiner-E. M. Bero Attorney-Brown & Mikulka [57]ABSTRACT Photographic focus adjustment apparatus for varying the axialposition of a camera objective lens or lens element is disclosed in eachembodiment as comprising lens carriage means having external threads,lens carriage support means having internal threads mating with thethreads on the lens carriage means, sliding key means for preventingrotation of the carriage means with the carriage support means whileproviding freedom of axial movement of the carriage means, and manuallyoperable actuating means for effecting selective rotation of thecarriage support means to cause the carriage means and thus the lens (orlens element) to move along its axis. In one embodiment depicted thecarriage support means, as well as the carriage means, moves axiallyupon rotation thereof in such a way as to obviate exposure of anythreads to atmospheric dust and other foreign matter. In anotherembodiment disclosed, contamination of the threads is avoided by theprovision of an expansible bellows between the lens carriage means andthe camera housmg.

3 Claims, 12 Drawing Figures mums-m ems 3.709132 SHEET UF 4 Figt 10.

IN VE N TORS GEORGE J. FARRELL WALTER R. LYON LORING K. MILLS and BYREGINALD O. SFAW and PHOTOGRAPI-IIC FOCUS ADJUSTMENT APPARATUSBACKGROUND OF THE INVENTION This invention is directed to the provisionof focus adjustment apparatus which is particularly suited forincorporation in cameras constructed to fold very compactly face-downinto a self-contained housing. Conventional focus adjustment apparatus,such as the type '0 OBJECTS OF THE INVENTION It is an object of thisinvention to provide focus adjustment apparatus adapted for use infolding cameras of the nature described in which axial movement of aposition-adjustable objective or element thereof is confined to a locusof travel completely within the camera housing, thus precludinginterference with the erection or take-down of the camera irrespectiveof the focus setting of the objective.

It is another object to provide photographic focus adjustment apparatushaving the capabilities described, and which is sealed againstcontamination by outside dirt and other foreign matter.

It is a further object to provide photographic focus adjustmentapparatus which is highly precise and which may be calibrated quicklyand easily.

Further objects and advantages of the invention will in part be obviousand will in part become apparent as the following description proceeds.The features of novelty which characterize the invention will be pointedout with particularity in the claims annexed to and forming a part ofthis specification.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of theinvention, reference may be had tothe following detailed descriptiontaken in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary perspective view of a front assembly of aphotographic camera which embodies the principles of this invention; ahousing for the assembly is partially broken away to show internalcomponents which would otherwise be hidden;

FIG. 2 is a plan view of the assembly shown in FIG. 1 illustrating anadjustable lens carriage in its rearmost (infinity) position;

FIG. 2A is a view similar to FIG. 2, but illustrating the lens carriagein its forward-most (near limit) position;

' FIG. 3 is an enlarged fragmentary perspective view, partly brokenaway, of the focus adjustment apparatus shown in FIGS. l-2;

FIG. 4 is a perspective view of a key comprising part of the FIGS. l-3apparatus; 1

FIG. 5 is an enlarged fragmentary view, partly broken away, of acompound idler gear comprising part of the FIGS. 1-4 apparatus; elementsof the gear are lockable in a selected relative angular attitude toenable the apparatus to be calibrated;

FIG. 6 is a fragmentary perspective view, partly broken away, of asecond embodiment of the invention employing a compound lens carriagesupport;

FIGS. 7A and 7B are schematic sectional views of a portion of the FIG. 6embodiment, showing the manner in which axial displacement of a lenselement is achieved by compound movement of a lens carriage support forthe element; FIG. 7A shows the element as it might appear when adjustedto its rear-most (infinity) setting; FIG. 7B shows the element as itmight appear adjusted to assume its forward-most (near limit) setting;

FIG. 8 is a view of a key forming part of the FIG. 6 assembly;

FIG. 9 is a fragmentary perspective view, partly broken away, of a thirdembodiment of the invention; and

FIG. 10 is a front elevational view of the FIG. 9 embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings illustrate threeof the many possible implementations of the principles of the invention.For reasons which will become apparent as this description proceeds,each embodiment provides the capability of adjusting a lens, which maybe the lens in a one-element objective or a movable element of acompound objective. As made clear in the above-stated objects of theinvention, in each embodimentadjustment of the lens is effected withoutthe extension of any structure from the housing for the assembly.

Focus adjustment apparatus according to this invention is particularlyuseful in a folding camera which erects from and collapses into aself-contained housing. The first of the illustrated embodiments isshown in FIGS. I-S. FIG 1 illustrates quite clearly the need for a focusadjustment mechanism having the characteristic and capabilitiesdescribed. This figure shows a portion of a photographic camera 10having a front assembly I2.pivotally mounted on a housing 14 by pins 16,18. The camera is shown in its erected position with its front assembly12 in an operative attitude. The broken line outline of the frontassembly 12 illustrates the assembly 12 as it would appear when thecamera is collapsed for storage.

The bottom wall 22 of the housing 14 lies flush with the front surfaceof the front assembly 12 to thereby protect the lens and othercomponents susceptible of being damaged when the camera is in acollapsed condition.

FIG. 1 makes quite evident the need in a folding camera of theconstruction shown for a focus adjustment mechanism having the propertythat no structure extends forwardly from the front surface of theassembly 12. If a focus adjustment mechanism of any of the conventionaltypes (e.g., the rotatable barrel type) were employed in a camera asshown, it is manifest that the user would have to rotate the lens barrelto its rearmost (infinity) position before the camera could becollapsed. The undesirability of such a construction is selfevident.

By this invention manualmovement of an external operator forming part ofan actuating mechanism .effects an axial adjustment in the position of alens which has a locus of travel wholly confined within the frontassembly. The actuating mechanism will be described in detailhereinafter. FIGS. I-S disclose a first embodiment of the inventioncomprising a lens mount 24 securely retaining two fixed elements 26, 28of a compound objective lens. A movable front element 30 is capturedsecurely by an annular lens carriage '32. The lens carriage 32 hasexternal threads 34 which are preferably of the multiple-start type. Thelens carriage 32 is received in an annular carriage support 36 havinginternal threads 38 mating with the external threads 34 on the lenscarriage. As described in detail below, the lens carriage support 36 isrotated by a pinion gear 40 (see FIGS. 1 and 2) which meshes with gearteeth 42 on the outer periphery of the lens carriage support 36.

In order to prevent rotation of the lens carriage 32 with the lenscarriage support 36 sliding key means are provided. The sliding keymeans may take many forms but is shown in the FIGS. 1-5 embodiment ascomprising a key 44 which is received in an axial groove 46 formed inthe outer surface of the lens carriage 32.

As shown clearly in FIG. 4, the key 44 comprises part of an annularsplit ring 48 serving as a retainer for the key 44. The ring 48 isreceived in and frictionally retained by the lens mount 24. Rotation ofthe lens carriage support 36 while precluding rotation of the lenscarriage therewith causes the lens carriage to move axially in the lenscarriage support, the direction of axial movement being, of course,dependent upon the direction of the threads 34, 38 and the direction ofrotation of the lens carriage support 36. A shroud 50 is secured to thefront assembly chassis 52. The shroud 50 offers protection for the frontlens element 30 and the lens carriage support 36.

As suggested above, a manually operable actuating mechanism is providedto allow a user to effect axial adjustment of the lens or lens elementin accordance with this invention. In the FIGS. lembodiment theactuating mechanism is illustrated as comprising a manually rotatableoperator 54 which is mounted for rotation on the front assembly housing14. The operator 54 has on its external periphery bevel gear teeth 56.The bevel gear teeth 56 on operator 54 mesh with gear teeth 58 on abevel gear 60. The gear 60 is illustrated as being carried by a shaft 61mounted on the housing 14. The angular locus of travel of the bevel gear60 may be appropriately delimited by conventional stop means (notshown).

A spur gear 66 is rigidly attached to the shaft 61 and thus rotates inunison with the bevel gear 60. The spur gear 66 engages a pinion 68forming part of an adjustable idler gear 69 supported for rotation byascrew 70 (see FIG. 5). As will be explained in more detail hereinafter,for purposes of calibrating the apparatus the pinion 68 and companionpinion 40 are rotatable relative to each other and can be locked in anydesired relative position by tightening a lock screw 72 whichfrictionally presses the pinion 68 against pinion 40.The pinion 40meshes with the gear teeth 42 on the periphery of the lens carriagesupport 36.

FIG. 2 illustrates the described first embodiment with'the lens element30 set to its rear-most (infinity) position; FIG. 2A shows the apparatusas it might appear with the lens element 30 adjusted to assume itsforward-most (near-limit) position.

In operation, to adjust the position of the front elewhich acts througha gear train comprising operator 54, bevel gear 60, spur gear 66, andpinions 68, 40 to rotate the lens carriage support 36. As describedabove, rotation of the lens carriage support 36 causes the lens carriage32 and thus the lens element 30 to move axially in a direction dependentupon the direction of the threads 34, 38 and the direction of rotationof the operator 54.

In accordance with an aspect of this invention, calibration of theapparatus may be accomplished quickly and easily by first setting thefront lens element 30 to its infinity (rear-most) position. The lockscrew 72 is then loosened until the pinions 68, 40 rotate freely on theshaft of screw 70. The manual operator 54 is then rotated to apredetermined mark or position associated with an infinity focus settingof the objective. With the objective and the operator thus set incorrespondence, they may be effectively locked together by tighteningthe lock screw 74 which has the effect of joining the pinions 68, 40 soas to rotate as a single unit.

A second method of calibration may be employed with an arrangement asshown in FIGS.- l-5 wherein the key 44 is affixed to or a part of africtionally held retainer ring. To practice this calibration method,the retainer ring 48 is rotated with respect to the lens mount 24against its frictional engagement therewith to achieve correspondencebetween the settings of opera tor 54 and lens element 30. The idler gear69 in this arrangement need not be adjustable.

FIGS. 6-8 illustrate a second embodiment of the invention having theproperty that no threads in the focus adjustment mechanism are exposedto the outside at any time. This embodiment thus minimizes thepossibility of the threads being contaminated by foreign matter. To thisend, a lens carriage 76 supporting a lens element 78 is received in alens carriage support 80 which has a bore threaded only a portion of itsaxial length. The forward portion of the bore is smooth.

The lens carriage support 80 is received in a stationary primary support82 which, like the lens carriage support 80, has a bore defining threadsextending only a portion of the axial length thereof. FIGS. 7A and 7Billustrate the manner in which contamination suppression is achievedwithout requiring an abbreviation of the locus of travel of the lenselement 78. Referring to FIG. 7A, the smooth portion of the bore of thelens carriage support 80 is labeled W,,; the smooth portion of the boreof the stationary support 82 is labeled W It is readily evident from aninspection of FIGS. 7A and 7B that the total travel of the lens element78 is equal to W, W,;, the cumulative travel of the lens carriagesupport 80 and the lens carriage 76. It is also manifest that by thisarrangement no threads are exposed at any time.

FIG. 6 shows a structural implementation of the described secondembodiment of the invention. In FIG. 6, an objective lens is illustratedas-comprising a rear element 84, a middle element 86, and front element88. The rear element 84 and middle element 86 are captured and retainedby a lens mount 88.

Lens carriage 76 is illustrated as having defined on its outer peripheryexternal threads 77, which preferably are of the multiple-start type. Asbriefly described above, the lens carriage support 80 has a boredefining threads on but a portion thereof. The forward portion 92 of thebore is smooth and makes a close sealing engagement with the outerperiphery of the lens carriage 76.

The lens carriage support 80 has threads 94 defined on its externalsurface; the direction of these threads 94 is opposite to the directionof the threads on the lens carriage 76 and on the inner periphery of thelens carriage support 80. The threads 94 mesh with internal threads 97on the inner periphery of the primary support 82. In the FIG. 6embodiment the primary support 82 is integrally connected to the lensmount 88.

In order that the lens carriage support 80 may be selectively rotated,as by an external actuating mechanism such as is shown in FIGS. 1 -2,the lens carriage support 80 has defined on its external periphery gearteeth 98. The gear teeth 98 are superimposed on and coextensive withthreads 94. Alternatively, the gear teeth 98 may be separated axiallyfrom the threads 94, however, a loss of total carriage travel mustnecessarily result in such an arrangement. i

In order to preclude rotation of the lens carriage 76 as the lenscarriage support 80'is rotated, sliding key means are provided. In theFIGS. 6-8 embodiment the sliding key means is shown as comprising a key100 formed as an integral part of a retainer ring 102. The retainer ring102 is shown clearly in FIG. 8. The retainer ring 102 has a set ofoutstruck tabs 104 which are received in recesses 106 in the innerperiphery of the lens carriage 76 to thereby preclude rotation of theretainer ring 102 relative to the lens carriage 76.

The retainer ring also has a set of inwardly deflected tabs 108 whichbear against a marginal portion of the lens element 78 and thus serve asa retainer for element 78. The primary support 82 has a groove 110formed therein which functions to slideably receive the key 100.-

In operating, rotation of the lens carriage support, for example by amanually operable actuating mechanism as shown in FIGS. 1 and 2, effectsa rotation of the lens carriage support 80 to thereby cause a compoundcumulative axial movement of the carriage support 80 and lens carriage 76. This compound movement causes the lens element 78 to be displacedalong the optical axis thereof according to the sum of the displacementsof the lens carriage 76 and lens carriage support 80 (W W in FIGS 7A7B).

Calibration of the FIGS. 6-8 embodiment may be achieved by the samemeans and method as described first above with respect to the FIGS. I-Sembodiment.

FIGS 9-10 illustrate a third'structure contemplated for implementing theprinciples of this invention. This embodiment illustrates a frontassembly 112 'for a camera including a variable focus objective lens114. In accordance with this invention a focus adjustment mechanism isprovided for effecting selective movement of the lens 114 along theoptical axis thereof. The focus adjustment mechanism comprises anannular lens carriage 116 for mounting the lens 114. The lens carriage116 is received withinthe bore of a tubular lens carriage support 118.The lens carriage support 118 has internal threads 120 mating withexternal threads 122 on the periphery of the lens carriage 116.

Means are provided for rotating the support 118 I while precludingangular rotation of the carriage l 16 to thus effect axial translationof the carriage 116 along the optical axis of the lens 114. To this end,the illustrated embodiment includes a manually operable rotary actuator124 having on the periphery thereof gear teeth 126 which mate with gearteeth 128 carried on the lens carriage support 1 18.

The support 118 and the rotary actuator 124 are mounted for rotation bya pair of walls 132, 134 extending across a housing 135 for the assembly112 transverse to the optical axis of the lens 1 14. The walls 132, 134have a pair of circular openings, the margins of which support annularbearings 140, 142. A pair of sleeves 144, 146 found in the walls 132,134, respectively, define bearings for receiving axles 148, 150 on therotary actuator 124.

In order to prevent the lens carriage 116 from following rotation of thebarrel 118 while allowing axial movement thereof, the lens carriage 116mounts a key 152 in the form of a rod which is received in a slidingrelationship in the bore of a tubular keyway 154. y

In order to enable the lens setting to be calibrated during manufactureof the camera, the keyway 154 is illustrated as being angularlyadjustable. Numerous structures may be devised for effecting suchangular adjustability of the keyway 154; the disclosed arrangement showsthe keyway 154 as comprising part of a spring clip 156 which may beselectively positioned along an arcuate support mechanism 158.

It is manifest from an inspection of FIGS. l-2 and the above descriptionthat rotation of the actuator 124 by the camera operator will cause thelens carriage support 118 to rotate and, because of the angularstationarity produced by the key 152 and keyway 154, the lens carriage 1l6 and thus the lens 114 is displaced axially to adjust the focus of thelens 114.

In order to preclude entry of dust and other foreign matter into theadjustment mechanism and exposure chamber, in accordance with thisinvention a seal in the form of a bellows 160 is connected between thelens carriage 116 and the housing 135. The bellows 160 may be connectedto the housing 135 and carriage 116 by any conventional means. Thebellows 160 may be fabricated from rubber, plastic, or other suitablebellows construction materials. It should be noted that theextensibility requirements on the bellows are quite lax since it needonly extend a distance equal to the extent of travel of the lenscarriage l 16, for example, normally a minor fraction of an inch.

The invention is not limited to the particular details of constructionof the embodiments depicted, and it is contemplated that various andother modifications and applications will occur to those-skilled in theart. I

' Therefore, because certain changes may be made in the above-describedapparatus without departing from the true spirit and scope of theinvention herein involved, it is intended that the subject matter of theabove depiction shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:

1. In a photographic camera of the type having a variable focusobjective lens means with an optical axis and at least one movable lenselement, a position adjustment mechanism for varying the axial positionof said lens element to adjust the focus of said lens means having lenscarriage means mounting said lens element,

said carriage means having external threads, carriage support means forsupporting said lens carriage means for movement along said axis, saidsupport means having internal threads mating with said threads on saidcarriage means, and manually operable actuating means for effectingselective rotation of said carriage support means; the improvementcomprising:

a key member, comprising a cylindrical rod, affixed to and extendingfrom said carriage means parallel to said optical axis;

keyway mounting means, with an arcuate element centered on said axis;

keyway means, having a hollow tube; and

means for adjustably securing said hollow tube at a selected angularposition on said arcuate element, said hollow tube receiving saidcylindrical rod in axial sliding engagement while precluding angularmovement of said cylindrical rod, thereby preventing rotation of saidcarriage means with said carriage support means while providing freedomof axial movement of said carriage means,

2. In a photographic camera of the type having housing means, a variablefocus objective lens means with an optical axis and at least one movablelens element, and a position adjustment mechanism for varying the axialposition of said lens element to adjust the focus of said lens means,with lens carriage means mounting said lens element, said carriage meanshaving external threads, carriage support means rotatably mounted onsaid housing means for supporting said lens carriage means for movementalong said axis, said support means having internal threads mating withsaid threads on said carriage means and external gear means, an actuatorgear rotatably mounted on said housing and having a portion extendingfrom said housing for tactile engagement by an operator, and an idlergear supported by said housing so as to couple said actuator gear andsaid carriage support'means for transmitting rotation of said actuatorgear to said carriage support means; the improvement comprising:

a key member, being a cylindrical rod, affixed to and extending fromsaid carriage means parallel to said optical axis;

keyway mounting means, with an arcuate element centered on said axis;

keyway means, having a hollow tube; and

means for adjustably securing said hollow tube at a selected angularposition on said arcuate element, said hollow tube receiving saidcylindrical rod in axial sliding engagement while precluding angularmovement of said cylindrical rod, thus preventing rotation of saidcarriage means with said carriage support means while providing freedomof axial movement of said carriage means.

3. In a photographic camera of the type having housing means, a variablefocus objective lens means with an optical axis and at least one movablelens element, lens carriage means mounting said lens element, saidcarriage means having external threads, carriage support means rotatablymounted on said housing means for supporting said lens carriage meansfor movement along said axis, said support means having internal threadsmating with said threads on said carriage means and external gear means,and sliding key means for preventing rotation of said carriage meanswith said carriage support means while providing freedom of axialmovement of said carriage means; the improvement comprising:

an actuator gear rotatably mounted on'said housing having a portionextending from said housing for tactile engagement by an operator;

an idler supported by said housing so as to couple said actuator gearand said carriage support means for transmitting rotation of saidactuator gear to said carriage support means;

first and second pinions coaxially mounted on said idler gear forrelative rotation; and

means for locking said first. and second pinions together at a selectedrelative angular position.

1. In a photographic camera of the type having a variable focusobjective lens means with an optical axis and at least one movable lenselement, a position adjustment mechanism for varying the axial positionof said lens element to adjust the focus of said lens means having lenscarriage means mounting said lens element, said carriage means havingexternal threads, carriage support means for supporting said lenscarriage means for movement along said axis, said support means havinginternal threads mating with said threads on said carriage means, andmanually operable actuating means for effecting selective rotation ofsaid carriage support means; the improvement comprising: a key member,comprising a cylindrical rod, affixed to and extending from saidcarriage means parallel to said optical axis; keyway mounting means,with an arcuate element centered on said axis; keyway means, having ahollow tube; and means for adjustably securing said hollow tube at aselected angular position on said arcuate element, said hollow tubereceiving said cylindrical rod in axial sliding engagement whileprecluding angular movement of said cylindrical rod, thereby preventingrotation of said carriage means with said carriage support means whileproviding freedom of axial movement of said carriage means.
 2. In aphotographic camera of the type having housing means, a variable focusobjective lens means with an optical axis and at least one movable lenselement, and a position adjustment mechanism for varying the axialposition of said lens element to adjust the focus of said lens means,with lens carriage means mounting said lens element, said carriage meanshaving external threads, carriage support means rotatably mounted onsaid housing means for supporting said lens carriage means for movementalong said axis, said support means having internal threads mating withsaid threads on said carriage means and external gear means, an actuatorgear rotatably mounted on said housing and having a portion extendingfrom said housing for tactile engagement by an operator, and an idlergear supported by said housing so as to couple said actuator gear andsaid carriage support means for transmitting rotation of said actuatorgear to said carriage support means; the improvement comprising: a keymember, being a cylindrical rod, affixed to and extending from saidcarriage means parallel to said optical axis; keyway mounting means,with an arcuate element centered on said axis; keyway means, having ahollow tube; and means for adjustably securing said hollow tube at aselected angular position on said arcuate element, said hollow tubereceiving said cylindrical rod in axial sliding engagement whileprecluding angular movement of said cylindrical rod, thus preventingrotation of said carRiage means with said carriage support means whileproviding freedom of axial movement of said carriage means.
 3. In aphotographic camera of the type having housing means, a variable focusobjective lens means with an optical axis and at least one movable lenselement, lens carriage means mounting said lens element, said carriagemeans having external threads, carriage support means rotatably mountedon said housing means for supporting said lens carriage means formovement along said axis, said support means having internal threadsmating with said threads on said carriage means and external gear means,and sliding key means for preventing rotation of said carriage meanswith said carriage support means while providing freedom of axialmovement of said carriage means; the improvement comprising: an actuatorgear rotatably mounted on said housing having a portion extending fromsaid housing for tactile engagement by an operator; an idler supportedby said housing so as to couple said actuator gear and said carriagesupport means for transmitting rotation of said actuator gear to saidcarriage support means; first and second pinions coaxially mounted onsaid idler gear for relative rotation; and means for locking said firstand second pinions together at a selected relative angular position.